The parasite Toxoplasma gondii is both an important human pathogen and a model for other related intracellular parasites that are grouped in the phylum Apicomplexa. Intracellular survival requires a large number of adaptations many of which are mediated by regulated secretion of parasite proteins. Toxoplasma resides within an intracellular vacuole that is endowed with the ability to resist intracellular digestion and to support parasite growth. Like related apicomplexan parasites, Toxoplasma is highly specialized for proteins secretion having three distinct compartments that discharge sequentially on invasion of the host cell. They will define the mechanisms of calcium-regulated secretion in this organism and investigate the role of secretory proteins intracellular survival.